The invention relates to the attachment of a conduit to the heart, such as a conduit for connection to an implantable blood pump, or for attaching a conduit to a blood vessel, as in a heart bypass graft. Particularly, the method and apparatus according to the invention provides for the safe attachment of a conduit to a ventricle of the heart without the need for performing a normally requisite cardiopulmonary bypass.
Each year hundreds of thousands of patients undergo life saving heart operations which necessitate the use of a heart, i.e., cardiopulmonary, bypass. The cardiopulmonary bypass procedure enables surgeons to perform complex heart operations without the heart actively pumping or, in many instances, not even filled with blood. In its simplest form, the bypass can be thought of as a procedure that provides an alternate blood pathway around the heart to maintain the blood flow through the body's tissues while the heart, which normally provides this function, is being surgically repaired. Typically, persons needing implantation of a left ventricular assist device (“LVAD”) require the establishment of a bypass pathway.
During implantation of an LVAD the patient's left ventricle is isolated from the circulatory system so that it may be entered for purposes of installing the LVAD's inflow conduit into the apex of the left ventricle. It is important that this is accomplished without excessive blood loss or air entering the left ventricle and circulation. The patient's circulation is maintained by a separate bypass pump and oxygenator, which temporarily bypasses the left ventricle. Bypassing the heart has a variety of risks to the patient in addition to its related expense. The main hazards surrounding the use of a bypass involve blood damage and embolism to the brain and body. The risk of these hazards tends to increase in proportion to the amount of time the patient is “on bypass”. Typically, the outflow conduit of the LVAD is attached to the aorta with an inflow conduit being attached to the left ventricular apex. Attachment of the outflow conduit of the LVAD does not require the cessation of blood flow within the aorta. The LVAD outflow conduit is typically made of a biocompatible fabric, such as polyester, and has a flexible tubular shape that can be attached to the aorta through the use of a side-biting vascular clamp. After the conduit is sewn to the aorta, and the other components connected, the side-biting clamp is released to allow blood to enter the conduit. The attachment of the inflow conduit for the LVAD is more problematic since attachment to the left ventricular apex cannot be accomplished using the vascular connection technique. The inflow conduit of an LVAD typically has a rigid cannula portion which transverses the muscle of the left ventricular apex and is designed to remain open at all times. For the case of a continuous flow pump like the one outlined in U.S. Pat. No. 5,928,131, blockage of the inflow conduit by clamping the left ventricle could cause severe heart tissue and blood damage. Further, the cannula's rigidity prevents the use of a side-biting clamp. Unlike the aortic connection in which a longitudinal incision is made along the clamped arterial wall, attachment of the inflow conduit requires a circular incision be made through the apical ventricular wall. To quickly insert the inflow conduit into the circular ventricular incision would risk induction of an air emboli into the arterial system or excessive blood loss from the opened ventricle.
Accordingly, it can be understood that there is a need for a method and apparatus for safely attaching an inflow conduit of an LVAD to the left ventricular apex of a heart without the necessity for performing the conventionally necessary cardiopulmonary bypass.